This species looks similar to, and is closely related to, G. marginatus, which is now understood to be not one species, but a cryptic species complex of four separate species that live in the Indian and Pacific Oceans. It shares the … 展开

With the aid of a gas-filled sac in its stomach, G. atlanticus floats at the surface. Due to the location of the gas sac, this species floats upside down. The upper surface is actually the foot (the underside in other slugs and snails), and this has either a blue or blue … 展开

G. atlanticus preys on other larger pelagic organisms. The sea slugs can move toward prey or mates by using their cerata, the thin feather-like "fingers" on its body, to make slow swimming … 展开

• Valdés, Ángel; Orso Angulo Campillo (November 2004). "Systematics of Pelagic Aeolid Nudibranchs of the Family Glaucidae (Mollusca, … 展开

At maturity, G. atlanticus is usually around 3 cm (1.2 in) in length, though larger specimens have been found. It can live up to a year under the right conditions. It is silvery grey on its dorsal side and dark and pale blue ventrally. It has dark blue stripes on its head. It has a flat, … 展开

This nudibranch is pelagic, and some evidence indicates that it occurs throughout the world's oceans, in temperate and tropical … 展开

G. atlanticus can swallow the venomous nematocysts from siphonophores, such as the Portuguese man o' war, and store them in the extremities of its finger-like cerata. Picking up the animal can result in a painful sting, with symptoms similar to those caused by the … 展开